Control unit for main gas burners and pilot burners



y 1954 J. A. NELSON ETAL 2,682,922

CONTROL UNIT FOR MAIN GAS BURNERS AND PILOT BURNER'S,

Filed April 26. 1950 11V VZ-INTORS:

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Patented July 6, 1954 CONTROL UNIT FOR MAIN GAS BURNERS AND PILOT BURNERS James A. Nelson, Elmhurst, and Joseph M. Algino and Gene F. Webber, Chicago, Ill., assignors to Cribben and Sexton Company, Chicago, 111., a corporation of Illinois Application April 26, 1950, Serial No. 158,296

3 Claims.

This invention relates to an electric control unit for a main gas burner and pilot burner. The gas burners may be employed in driers, heaters, and in a great varity of apparatus in which heat is required for different purposes.

This application constitutes a continuation-inpart of our copending application Serial No. 116,332, filed September 17, 1949.

An object of the invention is to provide an electric control and ignition unit for gas burners and, more particularly, for a gas burner and a pilot burner used in connection therewith. Another object is to provide an electric control and ignition unit for gas burners with means provided for closing the gas supply line to the main burner until the gas pressure has reached a predetermined pressure. Yet another object is to provide a control for the gas supply line to the main burner with means for preventing the flow of gas through the line until the gas pressure in the main manifold is at least about one-half of full pressure or above a definite predetermined pressure. A still further object is to provide electric control apparatus for a gas burner and its pilot valve, the apparatus having a minimum of moving parts while at the same time requiring the pilot burner to supply a predetermined amount of heat before a solenoid control valve in the line leading to the main burner is opened. Yet another object is to provide a control system for gas burners in which there is greater safety against the bleeding or escape of gas without ignition thereof and in which there is substantially no adjustment required after the system is installed. A further object is to provide in apparatus as described equipped with a mercury bulb or other control, a by-pass and means for controlling the by-pass so that while the mercury bulb is cooling, and if the main valve is again reopened while the mercury bulb is cooling, there will be no raw gas bleeding from the main burner.

The control apparatus provides a full safety function with substantially less equipment than heretofore required. Other specific objects and advantages will appear as the specification proceeds.

The invention is shown in an illustrative embodiment by the accompanying drawing, which is a schematic drawing illustrating an embodiment of the invention.

In the embodiment illustrated in the drawing, apparatus is diagrammatically shown for the controlled heating of a clothes drier or other like apparatus. The main burner is indicated by the numeral [0 and a pilot burner is indicated by the numeral l l The gas is supplied from a manifold or main I2 from which there leads a smaller manifold l3. From the smaller manifold I3 there is a gas supply line H! leading to the main burner It and a smaller gas supply line [5 leading to the pilot burner l l. A valve in the manifold I3 is controlled by the valve knob or regulator [6 which is equipped with a stem leading to the valve (not shown) in the manifold IS.

A by-pass line I! is equipped with a valve I8 and preferably the valve is opened to a predetermined extent so as to supply just enough gas to the burner It as to keep it burning. Thus, if the main valve is closed and the solenoid valve is kept open while the mercury bulb is cooling, the burner I 0 is kept alight and should the main valve be turned on again, the gas thus fed will be burned.

The electric control unit preferably consists of a solenoid, a circuit thereof having a normally open switch, a diaphragm device for controlling the switch and operated by a pressure fluid in a bulb located adjacent the pilot burner and being only operable by the heat from this burner, and an ignition coil for the pilot burner and circuits controlled by a switch or switches operated by the opening and closing of the main valve control I6. We also prefer to equip the circuit with a thermostat for maintaining the heat below a predetermined limit or limits, and other safety switches which insure the closing of doors of the drier, etc. Blowers for the movement of air through the drier may also be provided and the motor therefor will lie within one of the circuits described.

In the illustration given, we provide an ignition or glow coil 2| adjacent the pilot burner II. A transformer 22 is preferably employed for lowering the voltage needed for the glow coil. The transformer, however, may be omitted if the necessary voltage may be supplied by other means. A lead 23 to the transformer is connected to the contact 24 adapted to be connected with the line 24 by the switch 25 upon the rotation of the valve handle l6. Another lead '26 from the transformer is connected through various lines to a contact 21 adapted to be connected by switch 23 to an incoming line 29.

Opposite contact 24 is the contact 24; and opposite contact 2! is the contact 27 In the structure shown, the switches 25 and 28 are shown in open position, but when the valve handle I6 is rotated to open the valve the switches are moved to the contacts 24 and 21 illustrated so as to close the circuit of the transformer 22 and thus cause the coil 2! to glow. This ignites the gas flowing from the pilot burner l I.

Adjacent to the pilot burner H is a bulb 30 which preferably contains an expansion fluid, such as mercury, and 'a conduit 3| leads from the bulb to a diaphragm or bellows 32. The bellows 32 normally draws the switch 33 to the position shown in full lines in Fig. 1 and against the contact 34. It will be understood that the natural resiliency of the bellows or springs therein causes the switch 33 to be drawn to the position shown when there is little or no pressure within the bellows. When the heat from the pilot burner exceeds a certain temperature due to a predetermined pressure within the manifold I3, the pressure created by the expansion of.

the mercury vapor causes the bellows (which is referred to herein as a diaphragm) to move to the right to bring the switch 33 into engagement with the contact 35. This closes the circuit in which the solenoid lies and causes the valve I 9 to open so that the gas will now flow through the main line l4 to the gas burner it.

The circuit of the solenoid includes a lead 36 from the contact to the solenoid and also a lead 3'! connected to the contact 24* of the switch 25 through a branch lead 31 We prefer to interpose in the lead 3'! a thermostat 38 which is normally closed but which opens when the temperature within the drier or other device exceeds a predetermined limit. It will be understood that the thermostat, which is i llustrated diagrammatically as a bimetallic element, may be any type of thermostat and preferably is of the type which may be adjusted for different temperatures.

If desired, the lead 31 may also be provided with a switch 39 connected to the door of the drier and which will be closed when the drier door is closed.

If a blower is used in the drier, the motor is therefor may be connected in the circuit as illustrated, and the ballast fill may also be as shown in the circuit to limit variations in current in the circuit. An indicator light 4i may be included in series with the ballast to indicate energization of the motor.

If desired, a timer may be provided for breaking the circuit at a predetermined time so as to close off the burners, motors, etc. and the breaking of the various circuits may be after any desired timing intervals. In the illustration given, we have shown diagrammatically a timer &2 which may be actuated by clockwork or by electrically-cperated means for closing the switches 43, M and 45. In the illustration the timer 42 is of the usual construction and includes a timer motor 45 in series with the switch d5. Closing of the switch :35 completes the timer motor circuit and the timer then operates in the customary manner to interrupt the operation of the apparatus after a predetermined time interval. Since timers of this type are well known in the art, a further description is believed unnecessary. Since such timing structures are well-known and the operation thereof well understood, it is believed unnecessary to show further details.

Operation In the operation of the drier illustrated, valve 16 is opened, thereby bringing switch 25' into engagement with contact 2 3 and switch 28 into engagement with contact 27. The transformer -22 is thus energized and thereby the glow coil 2| is also energized. Gas fiows to the pilot burner H and is ignited by glow coil 2|. The flames from the pilot burner heat the mercury bulb 30, thereby causing expansion of the mercury contained within the bulb and bringing switch 33 into engagement with contact 35. The solenoid 2!] is thus energized so as to open the valve I9. Gas may then flow through the pipe it beyond valve I9 to the burner [0. The gas flowing from the burner I0 is ignited by the pilot burner II.

The by-pa'ss line I! supplies gas from manifold [2 to line 14 and, as previously pointed out, the valve 58 is so adjusted that a small amount of gas is always allowed to flow through it to the line M. This amount of gas is suflicient to keep the burner l0 lighted but not enough to furnish heat in any substantial amount. The mercury bulb 30 cools under this operation and eventually the switch 33 is brought back into engagement with contact 34.

Assuming that the clothes drier has not reached its maximum temperature and the thermostat 38 is still in the closed position, and the timer is still in the closed position, and that the main burner is still in full operation, if at this point the housewife should turn off the main switch It, switch 28 will be brought into engagement with contact. 2'! and switch 25 will be brought into engagement with contact 24 The mercury bulb, being still in a hot condition, will keep switch 33 in engagement with contact 35, thereby energizing solenoid 2t and thus maintaining the valve open. The flow of gas to lines i i and to the line of the pilot burner will be shut off when valve is is closed but a small amount of gas will continue to flow from manifold i2 through valve 18, line ll, line Id, through solenoid valve 19, and to the main burner It. Thus this small amount of gas will keep the main burner ID ignited but, by reason of the absence of heat from the pilot burner, the mercury bulb will cool, eventually bringing switch 33 into engagement with contact 34 and causing the solenoid valve [9 to close. This will shut oif the gas to the main burner It and return the entire control system to its initial condition.

Should the housewife desire to turn the drier on prior to the cooling of the mercury bulb 30, the gas flowing from manifold [2 through lines it and M and reaching the main burner will burn there at the full rate. At this time gas will aiso ilow through the valve it to pilot line it: and to the pilot burner ll. The pilot burner II will reignite from the main burner H3. The system will then continue to operate as such until either the thermostat St has reached its set limit or the timer breaks the circuit.

Under another condition, if the housewife after loading the unit with clothes and allowing it to operate for its maximum period of time, returns later to find the unit shut off and the clothes dry, and for some reason desires to dry an additional load, she need only insert the load and reset the timer. The system will take over automatically to provide full safety from this intermediate starting point. An important feature of the system thus described permits the burning of gas at a greatly reduced bypass rate while the mercury bulb is cooling and before the system cycles to its original position. If at any time the main valve is turned on while the mercury bulb is cooling, there will be no raw gas bleeding from the main burner since any gas to the main burner is ignited' by the flame always retained on the main burner except when the system is in that portion of the cycle to automatically operate through the complete cycle.

Instead of the manual operation described, the timer 42 is effective after the time is set, which is generally a manual operation and also closes switches 43, 44 and 45, for opening the switches 43, 44 and 45 and terminating the operation.

All of the results set out before are to a great extent achieved by the control operation of the solenoid 20 by means of the solenoid circuit arrangement. When the valve I6 is opened and the timer 42 set, the switch 28 engages contact 2'! and connects one side of the power input through timer switch 44 to the switch 33. After the switch 33 is forced against contact 35 by the expansion bellows 32, as previously described, the solenoid circuit is completed through lead 35, solenoid 20, lead 31, switches 38 (which is normally closed) and 39, and lead 36 to the other side of the power input. When the temperature exceeds the setting of the thermostatic switch 38 it opens (as shown) breaking the circuit and deenergizing the solenoid. The pilotburner, however, continues to be ignited. The same condition exists when the time for which the timer is set elapses and switches 43, 44 and 45 open. The circuit is broken and the solenoid is deenergized. Again the pilot burner continues to be ignited. When the valve [3 is closed the timer and thermostatic element are bypassed and the solenoid circuit is completed through switch 25, contact 24 leads 31 and 31, the solenoid 20, lead 36, contact 35, switch 33, and back to the opposite side of the input through the contact 2'! and switch 28. The main burner is still ignited, being supplied with fuel through bypass ll, etc., and until the member 30 cools and the bellows 32 withdraw the switch,33 from the contact 35.

It will be understood that the drier apparatus described may be modified in many ways and many electrically-operated devices may be placed within the circuit. For example, a germicidal lamp may be provided and an electric humidity thermostat may be provided if desired. Such devices may be added without modifying the operation of the system above described.

In the foregoing structure the valve control l6 may be arranged for controlling only the flow of gas to the pilot burner, the gas line to the main burner remaining always open except for the soleno d-controlled valve. We prefer, however, to employ the valve for controlling the flow of gas both to the main burner and to the pilot burner conduits.

The structure shown sets out fully an illustrative system and may be modified widely to meet the requirements for difierent heating, drying, or conditioning devices. The control unit, while shown in expanded form in the illustrations given, is actually a highly compact structure and is readily installed in a conventional drier or heating device and when installed requires only two conventional and simple gas rate adjustments. The moving parts are reduced to a minimum while the structure at the same time provides the utmost in safety control. Unless the pressure in the gas line is above a predetermined point and unless a suitable source of ignition is available, the solenoid valve in the main gas line will not open and gas thus cannot escape or leak.

While in the foregoing specification we have set forth wiring layouts and structure in detail for the purpose of illustrating embodiments of the invention, it will be understood that such details of layout and arrangement may be varied widely by those skilled in the art without departing from the spirit of our invention.

We claim:

1. A control unit adapted to be used with a main gas burner and a pilot gas burner and equipped with a valve controlling the flow of gas to the pilot burner and to the main burner and having a second valve interposed between the first-mentioned valve and the main burner for controlling the fiow of gas thereto, comprising a normally open bypass around said first-mentioned valve, an ignition coil adapted to be supported adjacent the pilot burner, a circuit therefore, a solenoid for opening and closing said second valve, a separate circuit for said solenoid, a single pole double throw switch controlling the current flow in both of said circuits, said switch being closed in one of said circuits when open in the other of said circuits, heat-responsive means controlling said switch and including a switch in said solenoid circuit for opening said circuit when the temperature to which the thermostat is exposed exceeds a certain point.

3. A control unit adapted to be used with a main gas burner and a pilot gas burner and equipped with a first valve controlling the fiow of gas to the burners and a second valve controlling the fiow of gas to the main burner, said first valve being equipped with a normally open bypass therearound, comprising an ignition coil adapted to be supported adjacent the pilot burner, a circuit therefore, a solenoid for opening and closing said second valve, a separate circuit for said solenoid, a single pole double throw switch controlling the current flow in both of said circuits, said switch being closed in one of said circuits when open in the other of said circuits, heat-responsive means controlling said switch and including a heat-responsive element adjacent said pilot burner, said means operating to close said ignition coil circuit when said element is below a predetermined temperature and to close said solenoid circuit when above said predetermined temperature, and a double pole double throw switch adapted to be actuated by the operation of said firstmentioned valve to complete the ignition coil circuit when the valve is opened and to complete the solenoid circuit when the valve is closed.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,844,959 Hulse Feb. 16, 1932v 2,048,162 Kriechbaum July 21, 1936 2,115,988 Furlong May 3, 1938 2,164,511 Furlong July 4, 1939 2,192,631 Beam Mar. 5, 1940 2,269,157 Levine Jan. 6, 1942 2,479,797 Wasser Aug. 23, 1949 2,486,306 Main Oct. 25,1949 2,489,794 Main Nov. 29, 1949 2,516,504 Cerny et a1. July 25, 1950 

